(A, E and I) TRPC4-expressing Xenopus oocytes were held at −40 mV and perfused with increasing concentrations of GFB-9289 (A), GFB-8438 (E) or GFB-8749 (I) to test the potential activation effect. 0.1 or 1 µM (-)-Englerin A (EA) were given at the end of recording to confirm the functional expression of TRPC4. (B, F and J) After activation of TRPC4 with 10 nM (-)-Englerin A, various concentrations of GFB-9289 (B), GFB-8438 (F) or GFB-8749 (J) were given together with 10 nM (-)-Englerin A to test the inhibitory effect. (C, G and K) Hill equation: y = 1/(1+ (IC50/x) ^ n) was used to fit the dose-inhibition curve, where IC50 is the 50% inhibitory concentration, x is the concentration of the ligand and n is the Hill coefficient. (D, H, and L) Sufficient GFB-9289 (D), GFB-8438 (H) or GFB-8749 (L) were used to fully inhibit 10 nM Englerin A-induced inward current, which can be reactivated by 1 µM Englerin A. Symbols with error bars represent mean ± SEM (n ≥ 3). The colored bars between the dashed lines indicate the concentration of compounds which was kept constant over time.